This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 21 |
| 6 | 68 |
| 7 | 208 |
| 8 | 612 |
| 9 | 1752 |
| 10 | 4916 |
| 11 | 13588 |
| 12 | 37128 |
| 13 | 100548 |
| 14 | 270404 |
| 15 | 723208 |
| 16 | 1925844 |
| 17 | 5110644 |
| 18 | 13524872 |
| 19 | 35713828 |
| 20 | 94140900 |
| 21 | 247806600 |
| 22 | 651572660 |
| 23 | 1711695508 |
| 24 | 4493475336 |
| 25 | 11789439876 |
| 26 | 30917835908 |
| 27 | 81053196808 |
| 28 | 212426303892 |
| 29 | 556607396532 |